than my Quick Draw II or the Garrett GHTAx 500 I just sold on Ebay. I kept the QD II because it's a coin magnet from clads on up.
With the Garrett and the bounty hunter, I can't tell the difference between foil, pull tabs, nickels.
Here's how I do it with the Cibola: Hunt with discriminator all the way down. Find a target. Listen for the loud extra crisp sound aluminum makes ( a little smother for pull tabs ) when not too deep ( say 4" or less, maby 3" ). Now I can thumb my discriminator knob to find the break up or knock out point. Compare that to the sound. Do they both indicate aluminum or pull tab?
Next I can turn my threshold down and pass coil over it again which gives me more information pertaining to depth, size, density, ect.
When I turn the threshold down I automatically stop it at the threshold point because I know where it is. Now I'm ready to push the pin point button, not to pin point but to scan in threshold based non motion all metal mode. That tells me info on size, depth and things around the target that may have an effect. For instance, Is it long? Is it wide? Does it have more than one part? If it's aluminum that's not too deep it screams in AM.
There's more to it but that's a start.,
Small aluminum that's deep ( say past 4" approx ) can sound just like a good target. But as as I remove dirt and don't find target when I think I should and the signal starts sounding like aluminum, it usually is and I usually go ahead and dig it at this point if I can't make a positive ID.
Aluminum cans are long and wide. They scream at me. I can not discriminate them out completely. I seldom dig one now with my Cibola. They are obvious.
Aluminum is found in so many shapes, sizes and thicknesses it may never become possible to ID it all. But Cibola, my first and only Tesoro does a good job as far as I'm concerned. I can work with that
I hope this helps, hope I didn't go over board.
Good hunting